milkweedTOP
A monarch butterfly on common milkweed. Photo by Betty Hall.
I’m going to start this column with the punch line. Monarch butterflies need milkweed as a host plant for their caterpillar stage. Milkweed is disappearing, and so these beautiful flying jewels are in some peril. Our gardens can help save the monarch butterflies. Plant milkweed, everybody.
And now, the details:
Monarch butterflies cannot withstand freezing temperatures and so are not able to overwinter as many other butterflies do. Around October they begin their migration south and west to get to warmer climes in Mexico and parts of Southern California. Once there, they hibernate on specific types of trees: the oyamel fir in Mexico and the eucalyptus tree in California. They use the same trees each and every year. How amazing, when you consider that they aren’t the same butterflies that arrived the year before.
This makes them very vulnerable. The crucial overwintering sites are under threat. Habitat destruction tends to occur because people want to cut down the trees to use the lands for homes, farms and roads.
In the spring the monarchs must head north again because their larval food plants –– the milkweeds –– do not grow in the overwintering locations.
Back they come. An individual monarch butterfly doesn’t live very long, though. The females lay eggs along their return journey then die; the eggs hatch and the new butterfly continues north, and so on. By the time they get here, we may be seeing the third or fourth generation of travelers.
This spring’s monarch count is, once again, down 20-30 percent. There are many causes for this decline, including habitat destruction in their overwintering sites. Here in the United States, we can point to our use of Roundup-resistant corn and soybean crops which allow the fields to be sprayed with this noxious herbicide that kills everything, including milkweed. Monarch Watch estimates that more than 100 million acres of milkweed habitat are now gone and planted to Roundup-resistant crops. We also mow our roadsides which removes yet another habitat for milkweed plants.
This is where the encouragement to plant milkweed comes in. If we all have a good patch of it in our gardens, what a difference that would make.
And we would just be adding beauty to our gardens in the process. The various milkweeds are very good-looking native plants so, for our home landscapes, this is a win-win proposition.
Swamp milkweed (Asclepias incarnata) is an erect, clump-forming plant with pink blooms that grows to about three feet tall. Butterfly milkweed (A. tuberosa) is lower growing and has brilliant orange blooms. Butterfly milkweed does not transplant well due to its deep taproot, so once established it is best to leave it undisturbed. While Common milkweed (A. syriaca) is a wonderful plant, it spreads by rhizomes. This makes it a very aggressive plant, probably not suitable for small landscape plantings unless you’re willing to dig it out when it appears in an undesirable spot. Purple milkweed looks similar to common milkweed except that its flower color is a rich red-purple and it will not spread aggressively. It seems to prefer a bit of shade but will do well in the sun if it gets deep, regular watering. Plant milkweeds in loamy soils since they don’t do very well in heavy clay. There are many more species of milkweed than I’ve noted, but this is a good start.
These wonderful plants are easily available locally. Springhouse Gardens and Michler’s carry a good variety of native plants. Shooting Star Nursery, located in Georgetown, is a native plant Mecca. Dropseed Nursery is another incredible native plant resource and well worth a visit. They are located in Goshen, just outside of Louisville.
Milkweeds also attract other butterflies as a nectar source for the adults. More than 42 species nectar on common milkweed, 22 on swamp milkweed and nine on butterfly milkweed.
The time to get these plants into your home landscape is now. If you can, add them to your garden in few locations, with several plants in each spot. When you see the monarch butterflies floating about, you will know you have done a good thing.